Browsing by Author "Dr. Samia Aslam"

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Multicomponent Photoluminescence Emission Tuning in CoS/Se core-shell Quantum Dot Thin Films for Light Emitting Applications
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2023) Moheem Arbab; CUI/FA21-RPH-028/LHR; Dr. Samia Aslam; LHR TP 8594
In this work, novel sulfide-based chalcogenide core-shell quantum confined structures Cobalt Sulfide/Selenide (CoS/Se) will be synthesized by a facile wet chemical route and will be deposited onto conducting oxide-coated glass substrates as thin films via spin coating technique. Depending on temperature and reaction time, the hot injection method will synthesize the core-shell structure. The QD dispersions will then be deposited onto conducting oxide-coated glass substrates (FTO) under variant deposition conditions such as varying the number of deposition cycles. RAMAN spectroscopy is used to study the vibrational modes, identify structures, and detect oxygen-related defects. The Raman analysis clearly shows the dominant Raman modes of CoSe. The PL spectra show the emission of CoS, CoSe, and CoS/CoSe in the visible region. The band samples' band gaps, particle sizes, and Urbach energies were timed by analyzing absorbance spectroscopy (UV- VIS Spectroscopy) measurements. The ellipsometry measurements were done to study the refractive index, extinction coefficient, and transmittance of different layered spin-coated thin films of CoS/CoSe core/shell QDs. These FTOs don’t behave as a polarizer. The synthesized CoS/CoSe Core/ shell QDs can be the potential candidate for optoelectronics devices.
Nitrogen(N)-Coordinated- Fe/Cu- ZIF Derived Carbon Nanostructures for Energy Devices
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2022) Usama Zia; CUI/SP21-RPH-022/LHR; Dr. Samia Aslam; LHR TP 8166
Recently, 2-D metal oxide frameworks (MOFs) have exhibited great potential for energy storage devices including supercapacitors and batteries. This is due to their superior and highly tunable porous, structural, and morphological features. Zeolite imidazolate frameworks (ZIFs) are highly chemically, and thermally stable class of MOFs which offer a wide variety of tunable porous structures and morphologies in comparison to widely used nano porous carbon which requires inert gas environment and high temperature treatment for large scale production and is therefore hazardous and expensive. In this work, we propose a N-coordinated Fe/Cu doped ZIF-8 derived carbon structure using facile room temperature sol gel and ion exchange method. The powdered material thus obtained will later be annealed in inert gas environment at high temperature to obtained N-coordinated Fe/Cu doped nano porous powdered carbon structures. The samples thus prepared will be characterized to study their structural, morphological, and electrochemical properties using Raman spectroscopy, Scanning electron microscopy (SEM) and Electrochemical impedance (EIS) spectroscopy measurements. The atomic composition will be studied using EdX measurements. The influence of bimetal doping for N-coordinated MOF derived carbon on the electrochemical performance will be studied using Nyquist and bode plots at electrode/polysulfide electrolyte interface suitable for QDSSCs. To the best of our knowledge, a bimetal Fe/Cu doped N-coordinated carbon-based electrolyte material has not been investigated for QDSSC solar cell applications. A possible insight into the defect states of the structures may also be investigated using Photoluminescent spectroscopy thus probing possible recombination sites influencing charge transport and loss mechanisms in the structures.
Spinel Ferrites Embedded Graphene Based 2D Electrode Materials for Energy Applications
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2022) Aysha Sarfraz; CUI/SP21-RPH-025/LHR; Dr. Samia Aslam; LHR TP 8169
Due to their favorable application and unique individualities like gas sensors, information storage system, magnetic bulk core, rechargeable lithium batteries, high density storage systems, catalyst, microwave absorbers, magnetic fluids and diagnostics from the perspective of basic research spinel ferrites have received a great deal of interest in recent years. In Spinel Ferrites nanoparticles an important understanding of crystal chemistry is critical a right synthesis procedure will conclude chemical composition and crystals with an easily identifiable lattice structure that will result in enhancing the chemical and physical properties. Due to its huge surface area and 2D honeycomb structure graphene is often used as a supporting material for other composite materials. Various composite materials may be embedded in the graphene net and interact with the environment effectively. Novel graphene(G) spinel ferrites MFe2O4 (M=Y, Bi, Co, Mo, Ce) composite material (GMFe2O4) was synthesized in this study and their characteristics as an electrode material for energy applications were explored. The structural properties were investigated via Raman spectroscopy and optical properties of material were studied by UV-visible and Photoluminescence spectroscopy. The electrochemical properties of the material were investigated using Cyclic voltammetry and Galvanostatic charge discharge.
Synthesis and Characterization of Metal Doped Kesterite (Cu2ZnSnS/Se) Derived Nanostructures as Light Absorber for Thin Film Solar Cell Applications
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2022) Muhammad Yasir Yaqoob; CIIT/FA19-RPH-038/LHR; Dr. Samia Aslam; LHR TP 7265
Kesterite materials (Cu2ZnSnS/Se or CZTS) exhibit encouraging potentials for energy conversion. In this study inexpensive, and cost-effective kesterite-derived nanostructures through metal doping in (CuZnXS, X=Ce, La, Mo) has been synthesized and test them as photo-absorbing materials for semiconductor-based thin- film solar cell applications. The photo-absorbance or light-absorption propensity of the photo-anode material in a solar cell is essential to the overall effectiveness of the solar cell. By adding a second layer of photo absorbance material, the photo-anode activity can be increased, which may also increase the amount of photogenerated electrons. Optical spectroscopy methods, such as UV-visible spectroscopy, is used to examine the photo absorption characteristics of the synthesized nanostructures. The optical band gap, % transmittance, extinction coefficient and refractive index of the kesterite material has been calculated and it was found that the band gap of the as synthesized kesterite material is varies in the range 1.125eV -1.5eV which is suitable as the absorber material for solar cell applications. The structural defects and recombination centers are examined using Photoluminescence spectroscopy. X-ray diffraction (XRD) and Raman Spectroscopy has been done to study the structure parameters and vibrational modes of the as synthesized kesterite material. The XRD patterns of the materials shows the formation of kesterite material with tetragonal structure for Ce-CuZnS and Mo-CuZnS and kesterite with monoclinic structure for La-CuZnS. The Raman spectra of all samples shows the characteristics modes of Cu- S, Zn-S and Ce2O, La-O and different modes of S-Mo-S in Ce-CuZnS, La-CuZnS, and Mo-CuZnS respectively.